1. Field of the Invention
The present invention relates to a connector-quipped electric-wire bundle comprising a plurality of electric wires and a connector provided on ends of the electric wires, and having a waterproof function.
2. Description of Related Art
As a water-proofing connector-equipped electric-wire bundle, there has been conventionally known a type disclosed in FIGS. 1 and 2 of JP 8-138795A. This type of electric-wire bundle comprises a plurality of electric wires and a connector, the connector having a plurality of connector terminals and a housing for holding the connector terminals. Each of the electric wires has an end portion where an insulating cover is removed to locally expose a conductor, and a portion rearward of the end portion to which a water-proofing plug made of pliable material, such as rubber, is attached; the connector terminal is attached across the water-proofing plug and the exposed portion of the conductor. The water-proofing plug has an periphery to make close contact with an inner surface of the housing, the close contact bringing an inside of the connector housing into a watertight state.
Each of the connector terminals has a conductor barrel to be crimped onto the conductor so as to enfold the exposed portion of the conductor from the outside, and a water-proofing-plug barrel to be crimped onto the periphery of the water-proofing plug in such a manner as to enfold the water-proofing plug from the outside. Thus crimping the conductor barrel to the conductor brings the conductor and the connector terminal into electrical conduction to each other. The water-proofing-plug barrel is crimped onto the water-proofing plug to restrain a mechanical load, particularly, a bending load, from acting on a section where the conductor barrel is crimped.
However, not all electric-wire bundles include same electric wires in terms of type or size; not a few electric-wire bundles include electric wires different from each other in type or size. Thus mixed wires possibly have a significant influence on mechanical characteristics, particularly, a tensile strength characteristic, of the entire connector-equipped electric-wire bundle.
Specifically, in the case of an electric-wire bundle which includes, as the above electric wires, a type of having a conductor with a small cross-sectional area and a small elongation occurring when it will have been broken under tensile load (breaking elongation), e.g., signal wire, and a type having a conductor with a large cross-sectional area and a large breaking elongation, e.g., power wire, a tensile load imposed to the entire electric-wire bundle will be ultimately concentrated on the electric wire having the relatively small breaking elongation. Moreover, this tensile load will be concentrated on a portion where the conductor is crimped to make its cross-sectional area be less than that of the other conductor. Therefore, even if the electric-wire bundle includes many electric wires, a tensile strength of the entire electric-wire bundle depends on a tensile strength (a minimum value of a tensile load enough to cause a pull-out or a breakage in a conductor-crimp portion of the electric wires) of a part of the electric wires having a relatively small breaking elongation, which may significantly deteriorate a tensile strength characteristic of the electric-wire bundle.
Particularly, recently used is an electric wire having a high tensile strength in spite of a small sectional area, such as, a wire having a conductor formed by twisting a plurality of strand elemental wires made of cupper around a center elemental wire made of stainless steel, or a conductor made of copper alloy having a tensile strength greater than that of copper. A breaking elongation of such a conductor is significantly small as compared with conductors of regular electric wires.